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EcoWatch: The Right Way To Water Your Grass

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FORT WORTH (CBS 11 NEWS) - During July of 2011 the North Texas Municipal Water District delivered 14 billion gallons of water to its 13 member cities. Last January that number was six billion — less than half the July amount.

So what’s the difference in water usage – in the summer we go ‘green.’ The largest irrigated crop in America is grass.

Do you have a yard? Want to save money, save our reservoirs and still have plenty of green?

Major components to achieving the goal are growing the right grass variety, having a good soil bed and learning how to water effectively.

The Fort Worth Botanical Garden is all set up for North Texans to learn great tips. Across the parking lot from the Japanese Botanical Garden, demonstrations are held year-round for all to see.

They plant the same combination of local grasses: three “warm season” grasses (ones bred to handle heat) and two “cool season grasses” (bred to be green in the winter).

All the grasses are in the same soil, getting the same amount of feed and sunlight. The difference is how much water they get. The amount of water given varies from 100% to 25% of what the plants would want/require.

For most who see the demonstration, it’s obvious that North Texans should be planting warm season grasses. There is a native grass, Buffalo grass, which does extremely well here and handles pests, weeds and fungus better than the others.

Having a landscape with warm season grass will mean that during the winter, from about mid-December to mid-March, the lawn will be brown.

Warm season grasses require much less water and are green during the summer. Grass is one of nature’s greatest natural air conditioners. Since it both absorbs sunlight and protects soil erosion, it provides balance to the urban heat island effect of concrete and engines.

Five thousand square feet of green grass cools the air just above it at a force equal to eight tons of air conditioning (about three homes worth). To prove this point, just take off your shoes, walk across your driveway, across some exposed soil (or dead, brown grass) and then onto green grass. You’ll forever feel the point of having a good stand of green on the hottest days. Having a house surrounded by green grass during the height of summer will also help your heating bill.

If you live in a high wildfire risk area, having your house surrounded by an island of green also goes a long way in keeping the fire at bay. Just look at aerial video of burned-out Texas neighborhoods and you can see this.

Most people don’t want to plant warm season grass because you can’t just throw out seed, like you can with cool season grasses. Sod or plugs must be put down in the late Spring over 8” of wet soil.

A couple of points here: the soil does have to be at least 8” deep. You need the depth to hide the water from the Texas sun. And second, never put sod down over dry soil. Turn it into mud and then lay the sod down. Almost all water districts that we know of allow an exception to watering restrictions when establishing new sod.

The grass will need about 30 days of frequent watering (about 2” a week) to get the yard going. After that, cut back to one-inch of water a week and the yard will be green through the hottest of summers.

THE ART OF WATERING

No more guessing what an inch of water looks like. You are going have to learn this down to a science, specific to your yard and your sprinkler system. Lay down about eight empty tuna cans (or any can with flat sides) and spread them around your yard. Turn on your sprinkler for 15 minutes, turn it off and then measure how much water is in each can. Do the math so you have minutes-to-an-inch ratio.

Now that you know how much to water, do it just once a week. Pick a time in the evening just as the sun is falling below the horizon (so there is no evaporation).

Break up your yard into zones with one zone equal to the area your sprinkler will cover without moving. Now start laying down your water a third of an inch at a time. Yes… you have to time out a third of an inch in a zone, move the sprinkler and cover the next zone a third of an inch. Cover all your zones and repeat three times. If you have three zones, you are going to move the sprinkler nine times.

Why such a fastidious program? Because it’s the only way it works. First off, we have clay soil around here, and it is slow to absorb water. If you try to water more than a third of your yard at a time the rest will simply run off into your sidewalk or street.

Second, the water has to get down to 4” down into the soil, where 90% of the roots are. The only way to get down there is to water slowly. If the water doesn’t go deep enough the roots will only grow a couple of inches deep, which will be a death sentence for your grass when the first heat wave hits.

You also have to physically check if the water got down to that depth. Take a spade shovel and go down about six inches and wiggle it back and forth to make some room. Then put your hand down there and feel (4 inches is about your index finger and past the first knuckle). It the water isn’t all the way down there, adjust your watering time to add another quarter-inch.

For a healthy lawn, it is crucial to water exactly like we’re outlining here. If you don’t, your lawn will either die or you’ll need twice as much water to survive the summer.

After you water, you must let the roots completely dry out before watering again (that will take about a week or less). The roots must dry out because it’s the only way to get oxygen in the soil.

So in summary, for a green yard in the summer in north Texas:

1) In the late spring, sod a warm-season grass (I like Buffalo grass) over 8” of very wet soil

2) Water one inch per week, ensuring the water gets 4” into the soil.

3) Do your watering on a single evening in three waves.

If all residents who have yards did the above it is estimated that it would reduce water consumption during the summer by 25%. It would also go a long way in keeping urban areas cool, reducing dust and helping fire fighters during grass fire season. Besides, it looks so much better to have green yards during the worst of a drought; it can help our sanity when we see nothing but brown pastures and woods everywhere else.